Depression is an affectivity disorder with which a depressive syndrome occupies the foreground, depressive meaning associated with depression or of a sad mood. Depressive diseases include unipolar mild depressions, dysthymia, melancholy, bipolar depressions, severe depressions with or without madness and moderate depressions (bipolar disease I, mania and severe depression; bipolar disease II, hypomania and severe depressions; cyclothymic personality disorders, hypomania and mild depressions). Those antidepressants of which the antidepressant action is based on an inhibition of the re-uptake of the monoamines noradrenaline (NA) or serotonin (5-HT) are widely used for therapy of depressions (Pacher, P., Kohegyi, E., Kecskemeti, V., Furst, S., Current Medicinal Chemistry 2001, 8, 89-100). Inhibitors of the re-uptake of monoamines are also used for treatment of anxiety disorders (Goddard, A. W., Coplan, J. D., Gorman, J. M., Charney, D. S., in: Neurobiology of mental illness, Charney, D. S., Nestler, E. J., Bunney, B. S. (eds.), Oxford University Press, New York, 1999, p. 548-563). Anxiety disorders are classified into generalized anxiety disorders, panic attacks, obsessive syndromes, social anxiety disorders, simple phobias, agoraphobias and posttraumatic stress disorders (PTSD).
In addition to the actual antidepressant action, inhibitors of the re-uptake of noradrenaline and serotonin also lead to an independent analgesic action by activating descendant pain inhibition paths at the level of the spinal cord. Inhibitors of the re-uptake of monoamines are employed clinically for monotherapy, and also as an adjuvant for treatment of chronic pain (inter alia neuropathic pain) (Sindrup, in: Yaksh, T. L. et al., Anesthesia. Biological foundations. Philadelphia: Lippincott-Raven, 1997, 987-997). There is still an urgent need for treatment of chronic pain in particular which is appropriate for the patient. Conventional opiates have a good action in the therapy of severe to very severe pain, while their activity on neuropathic pain is unsatisfactory.
The use of inhibitors of the re-uptake of monoamines is limited by side effects, such as e.g. accommodation disorders, serotonin syndrome or QT lengthenings.